The paper deals with tracing the role and respective significance of two multilateral mechanisms of building the state security, i.e. collective defence (military alliances) and collective security systems, in Polish security policy within the period spanning the regaining of its independence and modern times. The Authors pursue their assessment in chronological order, discussing the significance of the concepts of collective security and collective defence in Polish security policy in the three respective development phases of Poland’s modern statehood since 1918, i.e. the interwar period (the so called Second Polish Republic), the times of PRL (People’s Republic of Poland) spanning 1944–1989, and finally, in modern times, after 1989. Each time they discuss attendant determinants of Polish security policy within a specific period, indicate the role and significance attributed to collective defence and collective security in terms of enhancing Poland’s own security, sovereignty, and territorial integrity, as well as try to demonstrate how those concepts had actually underpinned the manner of implementing the country’s policy in practical terms, within the fold of such organisations as the League of Nations, UN, OSCE, Warsaw Pact, NATO, as well as in the course of other political endeavours of bilateral or multilateral scope. The Authors also set out to assess overall effectiveness of Polish security policy within the respective periods, as well as determine how the concepts of collective security and collective defence actually contributed to it, including the extent of coordination in specifically targeted political endeavours pursued by Polish government.